It has been reported that ternary copper/zinc oxide catalyst can be utilized for the synthesis of methanol from ternary H.sub.2 /CO/CO.sub.2 synthesis gas mixtures (Herman, et al., J. Catal. (1979), 56, 407 and Klier, Adv. Catal. (1982), 31, 243). It is well known to use as the third component Of the ternary catalyst, chromium (Davies, et al., U.S. Pat. No. 3,326,956; Brocker, German Patent 2,116,949) or aluminum (Brocker, German Patent 2,056,612; Cornthwaite, British Patent 1,296,212; Collins, German Patent 2,302,658; Casey et al., U.S. Pat. No. 3,790,505). It is also possible to prepare the Cu/ZnO catalyst in such a way that an active catalyst without the third component results (Stiles, U.S. Pat. No. 4,111,847; Herman et al., J. Catal. (1979), 56, 407). All of these catalysts can be utilized in the temperature range of 200.degree.-300.degree. C. and a pressure range of 2-100 atm. with ternary synthesis gas mixtures.
Stable catalytic activity is maintained with CO.sub.2 as the third component of the synthesis gas mixture. Examples of synthesis gas mixtures known in the art for production of methanol are: CO.sub.2 /CO/H.sub.2 =10/15/75 vol % (U.S. Pat. No. 3,326,956), CO.sub.2 /CO/H.sub.2 /CH.sub.4 =12/7/55/26 vol % where CH4 is an inert diluent (Cornthwaite, British Patent 1,296,212), and CO.sub.2 /CO/H.sub.2 =4.0/8.8/87.2 mol % (Stiles, U.S. Pat. No. 4,111,847). In the absence of CO.sub.2, all of the above systems undergo irreversible deactivation of the catalyst.
Of particular interest in the prior art of synthesizing methanol catalyst was the necessity of assuring that the materials used in catalyst formation were alkali free. For example, it has been stated that copper oxide/zinc oxide catalysts must contain less than 100 ppm of sodium. This level has been achieved by using ammonium carbonate or ammonium bicarbonate as the precipitating agent in the preparation of a catalyst from a metal nitrate solution. Sodium carbonate is typically used as the precipitating agent in forming the Cu/Zn/Al and Cu/Zn/Cr oxide catalysts. In these systems, the precipitated precursor is filtered and extensively water-washed to remove all alkali.